A: Any west-facing mountain turns golden, then pink because
it reflects light from the setting Sun. The Sun becomes dimmer and redder as
it sets and the mountain reflects this red light.

At sunset the red-orb Sun hovers on the horizon, changed from the blinding-white
disk we see at noon. Air, smoke, and dust cause this amazing transformation.
When the Sun is low, its light must go through a greater mass of air (about
38 times more) than when it's overhead. A sunray beaming through thick atmosphere
loses violet, blue, and green light on the way. Red light shines through relatively
unhindered. (See image below) That's why the white Sun turns red at sunset.

Light is made up of all colors: some
better at traveling straight to your eye than others. An incident sunbeam coming
into our atmosphere may smash into an air molecule or particle of dust or smoke.
If it does, its blue light is three times more likely than red to scatter. The
sunbeam re-radiates blue light in all directions. Less of the original light
gets through because of this scattering. The light that does get through is
red. (See USATODAY.com graphic link.)

Water and ozone enhance the reddening effect by absorbing violet, blue, and
green light.

The beauty of the show transcends the mechanics. As the Sun dips towards the
horizon, a ray beaming in through the atmosphere encounters more and more air
mass. And the Sun changes from yellow to wondrous colors of peach, magenta,
orange, pink, and finally red. The show changes daily with varying amounts of
dust, smoke, and water in the atmosphere. Never the same watermelon pink from
day to day. When the show's over, the deep blue shadow you see moving up the
mountain is the Earth's shadow.